1. Field of the Invention
The present invention relates to the dispensing of fluids stored under pressure, and, more specifically relates to an apparatus and method for dispensing of two fluids, mixing the two fluids and applying the mixture. Additionally, the present invention relates to a mechanism for maintaining a valve of an aerosol container in an open condition once the valve has been initially actuated to provide dispensing of substantially all contents of the container to be dispensed.
2. Description of the Prior Art
It is desirable to dispense fluid from a relatively inexpensive disposable package such as an aerosol container or similar pressurized container. In some applications, it is desirable to dispense fluids from two or more separate containers which contain different fluids. The fluids may be designed to react with each other and/or one fluid may be chemically unstable or uncompatible with one or more of the other chemicals. One use, for example, is in periodontal applications where it is desirable to mix two incompatible chemicals as disclosed in U.S. Pat. No. 4,521,403. One such device for dispensing fluids from a plurality of containers is disclosed in U.S. Pat. No. 3,613,956 to Roger L. McCulloch. The McCulloch patent discloses to two aerosol dispensing containers having hollow valve stems that are displaceable to discharge fluid under pressure from the containers. The mechanism for actuating the valve stems comprises a handle that pulls the valve stems inward toward their respective containers to actuate the valves. The valves are manually pulled inwardly by a trigger which is returned to its original position when it is no longer desired to dispense fluid from the aerosol containers. One of the primary disadvantages of a system that contains aerosol valves that may be repeatedly open and closed is that the fluid in the containers are not completely dispensed in one actuation of the valves. Since the pressures and the flow rates through the valves may differ from container to container depending upon the type of fluid being dispensed, the size of the valves, and the pressure in the container, the materials may be mixed in undesirable proportions. In addition, if the containers have equal pressures, but the flow rate through the respective valves is different, the head pressure in the mixing chamber may rise to a level where it prevents flow from one of the containers. Thus, the liquids will not be mixed in the desired proportions. Thus, it is desirable to provide a dispensing device wherein substantially all the fluid from each container is dispensed when the valves of the containers are actuated, and wherein the valves are locked in an open position. It is also desirable to provide a device and method of operation wherein both containers fully dispense and build up of pressure in the mixing chamber do not present further dispensing from one container.
In instances where a fluid is being dispensed from a single container or a plurality of containers containing fluid under pressure, it is desirable to insure that the substantially all of the fluid is expelled from each container when its respective valve is actuated. Thus, in prior art aerosol dispensing devices, the valve is typically held down either manually or by a mechanical locking means which are actuated once the valve stem is depressed toward the container. For example, U.S. Pat. No. 3,887,112 to Bolduc et al, U.S. Pat. No. 2,936,756 to Gabriel; U.S. Pat. No. 3,191,808 to Spalazzi et al and U.S. Pat. No. 3,245,586 to Haggit disclose mechanisms for maintaining one or more aerosol valves in an open condition.
When the valve is manually maintained in an open position, only one hand of the person using the dispensing device is available to manipulate other things. Thus, it is an object of the invention to provide a dispensing device which maintains the valve in the open position once it is actuated, without the need for the person operating the device to apply pressure to maintain the valve in its open position. It is also an object of the invention to provide a simple mechanism for maintaining one or more container valves in an open condition. Additional objects will be apparent from the description which follows